Fix RTPSender.SetReadDeadline crash

Add nil pointer check when calling SetReadDeadline. I don't believe this
can happen with WebRTC, but is possible with `ortc`.

A future improvement would be to cache the `SetReadDeadline` call. At
this time the complexity seems to outweight the reward.

Resolves #2889

errors.go

@@ -244,6 +244,7 @@ var (
 	errRTPSenderTrackNil             = errors.New("Track must not be nil")
 	errRTPSenderDTLSTransportNil     = errors.New("DTLSTransport must not be nil")
 	errRTPSenderSendAlreadyCalled    = errors.New("Send has already been called")
+	errRTPSenderSendNotCalled        = errors.New("Send has not been called")
 	errRTPSenderStopped              = errors.New("Sender has already been stopped")
 	errRTPSenderTrackRemoved         = errors.New("Sender Track has been removed or replaced to nil")
 	errRTPSenderRidNil               = errors.New("Sender cannot add encoding as rid is empty")

rtpsender.go

@@ -470,6 +470,10 @@ func (r *RTPSender) ReadSimulcastRTCP(rid string) ([]rtcp.Packet, interceptor.At
 // SetReadDeadline sets the deadline for the Read operation.
 // Setting to zero means no deadline.
 func (r *RTPSender) SetReadDeadline(t time.Time) error {
+	if r.trackEncodings[0].srtpStream == nil {
+		return errRTPSenderSendNotCalled
+	}
+
 	return r.trackEncodings[0].srtpStream.SetReadDeadline(t)
 }
 

rtpsender_test.go

@@ -504,6 +504,20 @@ func Test_RTPSender_RTX_Support(t *testing.T) {
 	})
 }
 
+type TrackLocalCheckRTCPReaderOnBind struct {
+	*TrackLocalStaticSample
+	t          *testing.T
+	bindCalled chan struct{}
+}
+
+func (s *TrackLocalCheckRTCPReaderOnBind) Bind(ctx TrackLocalContext) (RTPCodecParameters, error) {
+	assert.NotNil(s.t, ctx.RTCPReader())
+	p, err := s.TrackLocalStaticSample.Bind(ctx)
+	close(s.bindCalled)
+
+	return p, err
+}
+
 func Test_RTPSender_RTCPReader_Bind_Not_Nil(t *testing.T) {
 	track, err := NewTrackLocalStaticSample(RTPCodecCapability{MimeType: MimeTypeVP8}, "video", "pion")
 	assert.NoError(t, err)
@@ -528,16 +542,19 @@ func Test_RTPSender_RTCPReader_Bind_Not_Nil(t *testing.T) {
 	assert.NoError(t, peerConnection.Close())
 }
 
-type TrackLocalCheckRTCPReaderOnBind struct {
-	*TrackLocalStaticSample
-	t          *testing.T
-	bindCalled chan struct{}
-}
+func Test_RTPSender_SetReadDeadline_Crash(t *testing.T) {
+	stackA, stackB, err := newORTCPair()
+	assert.NoError(t, err)
 
-func (s *TrackLocalCheckRTCPReaderOnBind) Bind(ctx TrackLocalContext) (RTPCodecParameters, error) {
-	assert.NotNil(s.t, ctx.RTCPReader())
-	p, err := s.TrackLocalStaticSample.Bind(ctx)
-	close(s.bindCalled)
+	assert.NoError(t, signalORTCPair(stackA, stackB))
 
-	return p, err
+	track, err := NewTrackLocalStaticSample(RTPCodecCapability{MimeType: MimeTypeVP8}, "video", "pion")
+	assert.NoError(t, err)
+
+	rtpSender, err := stackA.api.NewRTPSender(track, stackA.dtls)
+	assert.NoError(t, err)
+
+	assert.Error(t, rtpSender.SetReadDeadline(time.Time{}), errRTPSenderSendNotCalled)
+	assert.NoError(t, stackA.close())
+	assert.NoError(t, stackB.close())
 }